$ git clone -n https://src.fedoraproject.org/rpms/rust-tiny-dfr.git /var/lib/mock/f38-build-side-42-init-devel-1186863-30623/root/chroot_tmpdir/scmroot/rust-tiny-dfr
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1186863-30623/root/chroot_tmpdir/scmroot/rust-tiny-dfr'...
$ git fetch origin 91c75b6fe29bdf89161cddf11a9abcae130fed78:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tiny-dfr
 * [new ref]         91c75b6fe29bdf89161cddf11a9abcae130fed78 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 91c75b6 Backport upstream commit for backlight udev rule